I've implemented Object Binding Patterns.

They can be used in methods, functions and declarations.

function test({x, y}) {
    print(x, y);
}
let {x, y} = {x: 0, y: 1};

test({x: 0, y: 1});     // Prints 0, 1
print(x, y);            // Prints 0, 1

They can have default values / initializers.

let {x = 5, y} = {y: 5};
print(x, y);            // Prints 5, 5

They can be nested.

let {x: {x, y}, z} = {x: {x: 0, y: 1}, z: 2};
print(x, y, z);         // Prints 0, 1, 2

They can have aliases.

let {x: foo, y: bar} = {x: 0, y: 1};
print(foo, bar);        // Prints 0, 1

They can also be exported.

export let {x, y} = {x: 0, y: 1};

I removed the throw from transformVariableDeclaration since TypeScript knows that all possible cases have been covered so it thinks the code is unreachable. It can be reached forcefully as evidenced in one specific test case. I removed this since TypeScript will never allow you to use a false keyword for a variable identifier.